Don't Let Mold Move In
Like mushrooms, molds are members of the fungi kingdom. They and the tiny spores they generate to reproduce need only water and something living or once living--like old wood--to eat. They thrive outdoors, hitchhiking into your home in dust and dirt on your clothes and shoes, on air currents, and in water that enters through cracks in walls and foundations. Once inside, they proliferate anywhere moisture exists. Notice a musty odor? You have mold.

In hot, humid months, more mold spores than usual surf the breeze. Check Web sites and newspapers for the daily mold count. On days when the count is high, close your windows (to keep spores out) and run an air conditioner (which dehumidifies). No AC? It's not ideal, but open your windows to keep indoor humidity down and prevent spores already inside from multiplying. No matter what the weather, the real key to avoiding mold problems is to keep things dry. What you should do:
Vent. Turn on an exhaust fan or open a nearby window while showering, bathing, running the dishwasher, or cooking, since all these activities produce water vapor. Make sure clothes dryers and all gas appliances are vented to the outside.

Monitor moisture. Use a hygrometer (about $20 at hardware and home stores) to check the indoor humidity level. If it exceeds 55 percent--most likely in summer--lower it by running an air conditioner or dehumidifier. In cold weather, indoor humidity should stay around 30 percent.

Fix leaks and dry waterlogged areas. If the pipes burst, the roof springs a leak, or a new crack in the foundation ushers water in, fix the problem ASAP. If you find a leak, dry the area pronto. "Within 24 hours, most molds are growing," says Berlin Nelson, PhD, an expert on plant pathology at North Dakota State University. Rent a wet-vac to dry floors. Use a space heater and fans to dry wallboard and ceiling tiles. Get professional help if you can't quickly manage solo.

Home Depot sell DIY test kits. They are petri dishes supplied by ProLabs in Weston FL. The petri dish method of testing is subject to many many variables and the results are vary unreliable. Even the best indoor air testing methods have a high probability of error. If you think you have a problem, hire a well qualified mold inspector or home inspector. Be cautious of those who over-sell the value and dependibility of air testing.

If you do use the petri dishes, keep in mind that the samples, when incubated, will almost always produce visible mold growth. If you mail those samples into the lab, they will identify the species. However, the petri method is qualitative, not quantitative. Often, I find petri dish testing is a useless endeavour.

Source(s): I teach mold inspection / testing along with building science
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